The present invention relates to a pressure exchanger for the transfer of pressure energy from a first liquid of a first liquid system to a second liquid of a second liquid system, comprising a housing with connector openings in the form of inlet and outlet openings for each liquid and a rotor arranged inside the housing to rotate about its longitudinal axis, said rotor having a plurality of continuous rotor channels with openings arranged around its longitudinal axis on each rotor end face, the rotor channels communicating with the connector openings of the housing through flow openings in the housing such that they alternately carry liquid at a high pressure and liquid at a low pressure to the respective systems during the rotation of the rotor.
A pressure exchanger of this general type is known from U.S. Pat. No. 6,540,487 B2. This type of pressure exchanger is not equipped with an external drive. To start operation, a complex method is required to cause such a pressure exchanger to start rotation of the rotor. The liquid stream is primarily responsible for the rotational movement of the rotor, passing through the flow openings in the housing from an oblique direction and striking the end faces of the rotor and the openings therein. During ongoing operation in a continuously operated system, an equilibrium state will develop in the pressure exchanger, so that the rotor rotates at an approximately constant rotational speed. Disadvantages of this design include a restricted operating range and mixing of the two liquids, which are found alternately in the rotor channels during operation.
U.S. Pat. No. 3,431,747 A and U.S. Pat. No. 6,537,035 B2 describe pressure exchangers in which the movement of the rotor is started by an external drive, and the rotor channels are constructed as bores with a ball arranged in each bore. This ball serves to separate the liquids flowing alternately into the rotor channels with a high pressure or a low pressure and to prevent mixing of the liquids in the bores. However, the disadvantages of this design include the arrangement, sealing and design of the ball, which acts as a separating element, and the respective seating. In addition, a complex high-pressure seal is required as a shaft seal in the area of a shaft bushing for the external drive.